Rather, Smith's real reporting involves looking into a certificate of some kind that Donald Trump posted after engaging in "Birther theorizing" (politico.com/blogs/bensmith/0311/
Trump_fails_to_produce_birth_certificate.html):

But after several New York City-based readers contacted POLITICO's Maggie Haberman, her call to city officials revealed that an actual birth certificate, which is issued by the Department of Health, would have the agency's seal and also a signature of the city registrar - neither of which the Trump document has. Officials said the city Health Department is the "sole issuing authority" of official birth certificates in New York, and that the document would clearly say so, and "city officials said it's not an official document."